The present invention relates to an optical device package structure for use in comparatively severe temperature environments of, for example, optical communications, illuminations, automobiles and so on.
Conventionally, there has been an optical device package structure in which an optical device of CCD (charge coupled device) or the like is mounted on a device mounting portion of a lead frame, the optical device and lead portions of the lead frame are connected together via wires, and the optical device, the wires and the lead frame are sealed with a light-transmitting resin (refer to JP 2000-173947 A). The light-transmitting resin is formed into a roughly rectangular parallelepiped shape of a material that has a satisfactory transmission property with respect to light incident on the optical device. A lens is formed integrally with the upper surface of the light-transmitting resin, so that the light is made incident on the optical device via the lens. Moreover, the lead portions of the lead frame protrude from side surfaces of the light-transmitting resin, and the optical device package is connected to prescribed electrodes by the lead portions.
However, in the conventional optical device package structure, the light-transmitting resin is mixed with no filler for reducing the coefficient of linear expansion in order to secure the light transmission property of the light-transmitting resin. Therefore, the coefficient of linear expansion of the light-transmitting resin is several times the coefficient of linear expansion of each of the materials of the optical device and the wires. As a result, there is a problem that, when the optical device package structure is used in a severe temperature environment where the temperature changes within a range of, for example, −40° C. to 105° C., the rupture of the wires and the destruction of the optical device are caused by thermal stresses in the light-transmitting resin. There is a further problem that the light-transmitting resin cracks.
It is an object of the present invention to prevent the occurrence of the rupture of the wires and the destruction of the optical device and prevent the light-transmitting resin from cracking with regard to an optical device package structure.